Well Ken Schramm, author of The Compleat Meadmaker
recommends (per 5 gallon batch) for medium fruit character:
Raspberries: 5-7 lbs.
Strawberries: 8-12 lbs.
As for pineapple, he doesn't mention it specifically, but pineapple is pretty high in both citric & ascorbic acids, so I'd treat it like citrus fruit: 6-8 lbs.
If you want to juice it, I'd say just juice the X lbs of fruit fruit & go with it whatever the juice amount is. You'll get more flavour with juice, so in theory you could use less fruit, but I'm not sure just how to calculate X amount of flavour from X amount of fruit juice vs X amount of sliced fruit in secondary.
Obvoiusly you might want more or less fruit flavour, depending on how much honey you want to come through. Fruit can easily overwhelm honey. BTW, you would do well to get a copy of Ken's book, it'll explain a lot of things & answer questions you haven't thought to ask yet. I have a copy on my shelf & still use it quite a bit.